Upgrades for Rotel RCD990

GerardA · 7th April 2005, 10:04 PM

I upgraded my Rotel RCD990 some years ago with OPA627 and 2604 to replace the NE5534 and NE5532. Now I'm thinking of adding a 2k resistor to the OPA627 between output and - rail and a 100 nF also between + and - rail.
What more can I do to improve this player? How big will be the improvement and did you try it yourself?
I'd like to make some easy changes first and maybe later the more complicated ones. Since I'm not really experienced in the miniature soldering I don't feel like experimenting too much. Changing the OpAmp's was already on the edge for me.

av98m · 8th April 2005, 03:05 PM

GerardA · 10th April 2005, 04:41 PM

Hi Av98m,
Thanks for your goodlooking pictures!
They look almost like the inside of my 990, is yours a 991?
The differences I spot are the double OPA627B at the output,
the red output caps, the green Wima blocks, a lot of blue caps and you replaced the two big ones. Is this all your work or is there more or is this due to the different model.
Which changes you think are most important and what brand/value did you use?

Thanks,

Gerard.

Gasho · 11th April 2005, 02:44 PM

I have RCD 990 . My modification was concentrated on power supply and ananalog section . In PS , I made changes by putting Schottky diodes in place of standard 1N4007 ones in all rectefiers , than i replace all caps in digital PS with Sanyo OsCon-s (one per supply rail before every D/A , digital filter , ad clock chip). In analog section I replace all Op-s with AD825 (silngle) and AD826(double) ops. All resistors where changed with Dale RN60/65 low noise resistors , and output caps (four of them) was replaced with 10uF MKP ( Mundorf) caps.

I saw the inside of RCD991 and now It´s clear to me why is RCD990 far better performer.

GerardA · 14th April 2005, 11:09 AM

Gasho,

This is my player!
I want to start with replacing the schotky diodes, do I need a special type for this?

I put the resistor and cap on the OPA627 and this makes the sound much better. Piano's shine like new, female voices sound not just like singing but you hear they do a lot more with their voice then just singing.
I'm thinking of putting extra resistor's on the OPA2604's too but they are double so do I put 2 resistors per opamp from the 2 output's to their common negative rail? Won't the output of one part of the chip influence the other part?

Joseph K · 15th April 2005, 03:09 PM

Hi,

May I be a little off topic, and ask about a special feature of my Rotel RCD990? What I found is that the output attenuation [which is controlled by the remote] is not functional. The strange thing is that the display responds to the remote commands, obediently stepping down / up the att. values in 5db steps, but then at the output actually happens nothing. Is it a failure in my unit, or is a "feature" present in other units as well?
I ask this, because I've bought this player used & without remote. Then I succeded in constructing a remote for it, but then found this "feature". It slightly disturbs me, and would be nice to understand - otherwise the unit works seamless, also the remote.
[This function is built in the PMD100 filter, and should be commanded by the microcontroller. In my unit the micro does not seem to issue the command.]

Thanks in advance!

george

GerardA · 15th April 2005, 03:19 PM

Hi Joseph,

This feature works in two steps,
First you decide how much attenuation you want and then push the mute button.

Joseph K · 15th April 2005, 03:29 PM

Great!

Thanks GerardA, I will try. Somehow I skipped this particular...

Ciao, George.

kasra · 15th April 2005, 04:17 PM

If your soldering skills are up for it, perhaps you should try the better "k" grade pcm63´s?

Also glue the powersupply capacitors so they are steady.

GerardA · 17th April 2005, 08:53 PM

Hi Kasra,

It's the desoldering of the two-sided board that wories me most.
Is the K-grade not supposed to have some adjustment?
In what way do you glue the capacitors, I have the idea they are already fixed tightly but maybe some extra treatment is possible?

7th April 2005, 10:04 PM	#1
GerardA diyAudio Member Join Date: Mar 2005 Location: nieuwegein	Upgrades for Rotel RCD990 I upgraded my Rotel RCD990 some years ago with OPA627 and 2604 to replace the NE5534 and NE5532. Now I'm thinking of adding a 2k resistor to the OPA627 between output and - rail and a 100 nF also between + and - rail. What more can I do to improve this player? How big will be the improvement and did you try it yourself? I'd like to make some easy changes first and maybe later the more complicated ones. Since I'm not really experienced in the miniature soldering I don't feel like experimenting too much. Changing the OpAmp's was already on the edge for me.

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8th April 2005, 03:05 PM	#2
av98m diyAudio Member Join Date: Jun 2004 Location: na

10th April 2005, 04:41 PM	#3
GerardA diyAudio Member Join Date: Mar 2005 Location: nieuwegein	Hi Av98m, Thanks for your goodlooking pictures! They look almost like the inside of my 990, is yours a 991? The differences I spot are the double OPA627B at the output, the red output caps, the green Wima blocks, a lot of blue caps and you replaced the two big ones. Is this all your work or is there more or is this due to the different model. Which changes you think are most important and what brand/value did you use? Thanks, Gerard.

14th April 2005, 11:09 AM	#5
GerardA diyAudio Member Join Date: Mar 2005 Location: nieuwegein	Gasho, This is my player! I want to start with replacing the schotky diodes, do I need a special type for this? I put the resistor and cap on the OPA627 and this makes the sound much better. Piano's shine like new, female voices sound not just like singing but you hear they do a lot more with their voice then just singing. I'm thinking of putting extra resistor's on the OPA2604's too but they are double so do I put 2 resistors per opamp from the 2 output's to their common negative rail? Won't the output of one part of the chip influence the other part?

15th April 2005, 03:09 PM	#6
Joseph K diyAudio Member Join Date: Dec 2004 Location: gran sasso	Hi, May I be a little off topic, and ask about a special feature of my Rotel RCD990? What I found is that the output attenuation [which is controlled by the remote] is not functional. The strange thing is that the display responds to the remote commands, obediently stepping down / up the att. values in 5db steps, but then at the output actually happens nothing. Is it a failure in my unit, or is a "feature" present in other units as well? I ask this, because I've bought this player used & without remote. Then I succeded in constructing a remote for it, but then found this "feature". It slightly disturbs me, and would be nice to understand - otherwise the unit works seamless, also the remote. [This function is built in the PMD100 filter, and should be commanded by the microcontroller. In my unit the micro does not seem to issue the command.] Thanks in advance! george

15th April 2005, 03:19 PM	#7
GerardA diyAudio Member Join Date: Mar 2005 Location: nieuwegein	Hi Joseph, This feature works in two steps, First you decide how much attenuation you want and then push the mute button.

15th April 2005, 03:29 PM	#8
Joseph K diyAudio Member Join Date: Dec 2004 Location: gran sasso	Great! Thanks GerardA, I will try. Somehow I skipped this particular... Ciao, George.

15th April 2005, 04:17 PM	#9
kasra diyAudio Member Join Date: Nov 2001 Location: Sweden	If your soldering skills are up for it, perhaps you should try the better "k" grade pcm63´s? Also glue the powersupply capacitors so they are steady.

17th April 2005, 08:53 PM	#10
GerardA diyAudio Member Join Date: Mar 2005 Location: nieuwegein	Hi Kasra, It's the desoldering of the two-sided board that wories me most. Is the K-grade not supposed to have some adjustment? In what way do you glue the capacitors, I have the idea they are already fixed tightly but maybe some extra treatment is possible?

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